1) Precision positioning. Now, we are mainly shooting skyline changing of cities by using Kessler Shuttle pod + Evolution head+ Oracle. The Kessler system works great. However, this is a long term work and requires us to go back to the SAME position and shooting at the SAME angle for many times. So, the precision positioning of the shooting position and angle is a desired.

We intend to use GPS to navigate the physical position, however, we finlay found out that the resolution of GPS we used is not sufficient to precision positioning our shuttle pod to a exactly SAME spot. We currently use tape to mark our tripod to record the shooting angle. It works, but not the best. Does anyboy here have a better idea for solving this problem?

2) eliminate or avoid the rail system from 'draw back shooting'. We meet a problem when we create a draw back shooting-the shuttle pod moving far away from the target in the rail during shooting. After shuttle pod moves a certain distance, the rail will be captured by the camera. Any one have any suggestion to solve this problem.

Thanks in advance for everybody who will repley

Wed Aug 08, 2012 12:24 pm

unozig

Joined: Fri Apr 03, 2009 6:15 pmPosts: 832Location: Middle Earth

Re: How to precision positioning of repeating timelaspe

Surveyors need to reposition their tripods over a survey mark on a daily basis. So a GPS will help you to navigate to within 5m of the mark then your notes and eyes take over. Survey marks come in all sorts of sizes and types eg. chalk marks, wooden pegs, steel pins.If unable to mark the ground surface we use 2x 5m hand measurement tapes to triangulate the position. The instrument has an optical square which allows you to position it over the mark but a plumb bob works just fine.

Once the tripod is positioned we sight 2 targets ideally +-45 degrees either side so the survey instrument is "synchronised" with the last setup.

Survey targets are used but a simple basic sighting of a landmark can be used, eg. telegraph pole, TV areil, edge of a building on skyline.

Remember to sight both the horizontal and vertical position simultaneuosly.

Thanks a lot for shareing your experience with us. I understand there no 'perfect' way to deal with that. However, I think those tips will help us better deal with this issue.

Thu Aug 09, 2012 8:33 pm

MikeA

Joined: Tue Nov 24, 2009 7:55 amPosts: 948Location: UK

Re: How to precision positioning of repeating timelaspe

Hi,To fine tune the target suggestions above, you could try "Onion skinning" your last session shot with your next session set up with a stop/motion programme.Example from Dragonframe : http://www.dragonframe.com/tutorials.phpJust a thought. MikeA.

To get the track out of frame when dollying back, use a hi-hat or other support to get the camera a bit higher above the track. In a pinch, a real small tripod on the trolley works. if you're planning on doing this more than once, a special support would be helpful. It doesn't need to be complicated. A box which fastens to the dolly with a 1/4-20 thread bolt to hold the camera on top of the box, for example.

For precisely re-positioning the rig, permanent markers like a nail-head in the floor would be ideal. In lawns or natural places a stake pounded into the earth until it is flush with the ground so nobody trips over it. Pounding in a little past flush is possibly better in high traffic areas but you will have to sweep away a little sand to find the top of the stakes when you return. If thats not allowed, maybe writing down or photographing existing mini-landmarks could help. For example, "the left front leg of the dolly support is at the intersection of the fifth floor tile from the west wall and the eighth tile from the north wall". This kind of strategy will depend a lot on exactly what kind of floor you have to work on. Your own equipment can be marked with little scratches showing where legs were extended to, the angle of the tripod head holding the dolly, etc. Wherever possible, having supports at one end of their travel would help. For example, all tripod legs at the front of the dolly are fully retracted, all legs on the tripod at the back of the track have the center section fully extended, etc. From there, the onionskin pictures taken at each end of the track should get you pretty darned close to being in exactly the same position.

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